1. Field of the Invention
The present invention relates to eyeglasses, and more particularly to a lens of eyeglasses for use in sports such as bicycle road racing.
2. Description of the Background Art
FIG. 8 is a perspective view showing eyeglasses for use in sports being actually worn by a person, which is disclosed in U.S. Pat. No. 4,859,048, and FIG. 9 is a view seen in the direction of arrows "c" in FIG. 8.
Referring to these figures, a lens 32 for eyeglasses affixed on a frame 33 is made of, for example, an integral transparent plastic as shown in FIG. 10, and its curved surface is formed of a part of the curved outer surface of a cylinder having a radius R. Therefore, eyeglasses 34 can serve as sunglasses for use in sports securing a wide view through lens 32.
In conventional eyeglasses as mentioned above, the field of vision through lens 32 does not come into question because the line-of-sight of a person is in the direction of the arrow in solid line in FIG. 9 in the normal usage. A person, however, sometimes bends forward to look ahead during the use. In this case, the line-of-sight is in the direction of the arrow in broken line in FIG. 9, and accordingly the line-of-sight is interrupted by the structure of a frame 33, so that a sufficient front view cannot be secured. Therefore, capability of assuring safety by sight is reduced especially when a bicycle is running at high speed with a person bent forward.